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C O N G R A T U L A T I O N S
You now have the easiest to use, least expensive, satellite tracking package
available in shareware. The capabilities provided by PC-TRACK were previously
limited to programs which were hard to use, expensive, and designed for
mini-computers or more expensive 80286 and 80386 based personal computers.
Now you can graphically track your favorite terrestrial satellites with ease,
accuracy, and money left in your pocket.
ABOUT THIS MANUAL
PC-TRACK was written to be simple enough to use without any documentation.
PC-TRACK incorporates context sensitive on-line help to assist with any area
of question. In an effort to make PC-TRACK as useful as possible, this manual
is also provided for your assistance. It will provide you with detailed
explanations of the way PC-TRACK works and its features. It will also will
provide you with helpful tips and information which will help you get the
most from PC-TRACK.
COPYRIGHT STUFF
PC-TRACK is marketed as SHAREWARE. IT IS NOT PUBLIC DOMAIN SOFTWARE! This
means that anyone can make copies of PC-TRACK to distribute to others for
the purpose of evaluating the package for usefulness. But if you decide that
PC-TRACK will be useful to you and decide to use it regularly, you must
register your copy. This means paying for the use of the software. See the
file called README on the disk or the messages in PC-TRACK for details on
how to register. All rights to PC-TRACK are held by Thomas C. Johnson.
PC-TRACK is Copyright (C) 1989 by Thomas C. Johnson.
PART I
INTRODUCTION AND INSTALLATION
GENERAL DESCRIPTION
PC-TRACK is a general purpose satellite tracking package designed to take
the complexity and confusion out of finding where an earth orbiting
satellite is in space and providing the antenna pointing data necessary to
transmit signals to or
receive signals from them.
HISTORY
PC-TRACK has its origin in a satellite tracking program I wrote to track the
OSCAR (Orbiting Satellite Carrying Amateur Radio) series of amateur radio
satellites back in 1980. That program was called OSCAR PATHFINDER and was
the front cover feature article in the March 1982 edition of "73 Magazine
For Radio Amateurs." That program was written for the Apple II plus computer
in Applesoft BASIC. It was a revolutionary program at that time in that it
was the only program that tracked satellites in real time (the Apple had no
clock) and displayed the satellite path on a map on the graphics screen. It
was capable of only tracking circular orbiting satellites, but that was not
a problem at that time because all of the amateur radio satellites were in
circular orbits.
OSCAR PATHFINDER was so enthusiastically received that I made the decision
to make some improvements to the program and offer it commercially. This led
to a venture called Computer Applications and I sold quite a number of
copies of Pathfinder II. I then developed a version of the program for the
TRS-80 Model III computer called Pathfinder III. After a year or so of
selling these packages, myself and my partner decided (for various reasons)
to pull the plug on this and go on to other things.
Later, with the launch of several elliptical orbit amateur satellites, I
tinkered with the program some more to include the math necessary to track
such satellites. This resulted in Pathfinder X, which was never published,
but I used it quite a bit at home for my own tracking needs. I had also
started rewriting the program in UCSD Pascal because that offered a much
more readable and manageable structure for the program.
When I got my IBM PC/XT clone in 1985, I had a desire to port Pathfinder X
over to my new "supercomputer" since it had an 8Mhz clock and would be able
to do faster computations and have better graphics capabilities. Well, after
many years of many distractions (other business ventures, kids being born,
moving, etc.) I have finally put together my idea of a nifty package for
tracking satellites, called PC-TRACK.
FEATURES
PC-TRACK provides the capability of managing two data bases. One for the
objects to be tracked, and another for the observation points. PC-TRACK has
the capacity for handling 100 objects and 100 observation points. These can
be easily entered and updated using built in modules.
PC-TRACK can track an object in real time or make predictions of satellite
position both forward and backward in time. Tracking can be paused at any
time for display analysis.
PC-TRACK can send the computed data to your printer at any time, either
printing all points computed or only those within range of the selected
observation point. PC-TRACK prints a header containing the object tracked,
observation point name and data, and column headers at the top of each page
to provide a neat, identifiable document.
PC-TRACK uses the standard EGA screen so you can use any of the many screen
dump or screen capture programs available to print or save displays.
PC-TRACK also has a configuration module which enables you to configure the
colors of the text screen to your liking and to setup the printer control
commands to be used by your printer for printouts. It also enables you to
define the disk and subdirectory where PC-TRACK will find the data files it
needs.
Finally, PC-TRACK has an on-line help system called PC-TRACK ASSISTANT built
in which is context sensitive. It provides help for whatever piece of
information you are entering or feature you are accessing. Once in the help
system, you may also browse through the rest of the help screens to get
information on whatever topic you desire.
SYSTEM REQUIREMENTS
SYSTEM: IBM PC/XT/AT or compatible.
DISPLAY: EGA (640X350 16 Color)
MEMORY: 512K
DISKS: 1 Floppy Disk (hard disk is better)
PRINTER: Any capable of printing at 5, 10, and 12 CPI,
and 12 LPI (any other will work but printouts
could run off page)
INSTALLATION
PC-TRACK is distributed on one 360K floppy. PC-TRACK includes all the files
and data needed to run. (Data should be updated as soon as possible to
insure predictions are accurate. Satellite data gets old after a couple
weeks. Besides that, PC-TRACK will most likely not have the location data
for your observation point.)
It is wise for you to immediately make a backup copy of everything on the
distribution disk to another disk. I recommend doing this by using the
DISKCOPY command. Put the original away as a master.
If you are using a hard disk. Make a subdirectory on it and copy all the
operational files to it. (Don't forget to change directories to the one you
just created before you begin copying.) You will not want to take up room
on your hard disk with the documentation and support files.
If you are using floppy drives, format a floppy disk with the operating
system on it and copy all the operational files to the new disk. You may
then put an AUTOEXEC.BAT file on it to have it automatically begin running
when you boot up. (Somewhere in the AUTOEXEC file have a line with "PCT" on
it.)
------- F I L E S P R O V I D E D -------
FILENAME DESCRIPTION
----------------------------------------------------------------
OPERATIONAL FILES
PCT.EXE PC-TRACK Satellite Tracking Program
WORLD.MAP Binary data for the world map used in the
tracking screen in PC-TRACK.
PCT.HLP Text file containing the PC-TRACK help
messages for the on line help.
PCTCOLOR.DEF Contains the system colors used for the text
screens in PC-TRACK.
PCTSYS.DEF Contains the system configuration parameters
and the printer control codes.
OBJECTS.DAT Data file containing satellite orbital
elements for each satellite in the data base.
OBSERVER.DAT Data file containing the location data for
each observation point in the data base.
DOCUMENTATION AND SUPPORT FILES
PCT.DOC This Users Manual
README Gives introductory information concerning PC-
TRACK.
--------------------------------------------------------------
PART II
O P E R A T I O N
GETTING STARTED
PC-TRACK is started from the DOS prompt by entering PCT <RETURN>. PC-TRACK
begins by presenting you with a pretty colored hello screen. There will be
a brief pause at this point while PC-TRACK loads in the help screens and the
world map. This takes a few seconds (depending on the computer used). You
will see a message at the bottom of the hello screen which says
"INITIALIZING... PLEASE WAIT." Once initializing is completed, you are
presented with the main menu screen. This is a small shadowed window on the
left side of the screen with the 4 main module options listed.
The four module options are SETUP, TRACK, CONFIGURE, and QUIT. Selecting
one of these options is done simply by moving the cursor (shown by selected
name being in a different color than the rest of the options listed) so that
it highlights the module desired and pressing the RETURN key.
USING THE ON-LINE HELP
The on-line help system is available from anywhere in the program and can be
accessed simply by pressing the F1 key. The information presented on the help
screen will be dependant on where you are in the program.
For example, if you are in the SETUP OBJECTS option with the cursor on the
NAME field and you press the F1 key, the help screen will pop up and give
you specific information on entering the NAME field data.
Once you are in the help system, you may browse through the information
provided by pressing the Page Up, Page Down, Up Arrow, or Down Arrow. Page
Up does the same thing as the Up Arrow key and Page Down does the same thing
as the Down Arrow key. You may get back to the original screen by pressing
the HOME key.
When going "down" in the system, you will be able to step through every
screen in the help system. When going "up", you will skip up to the top
screen of the previous major topic in the system. This allows you to move
quickly through the screens to the one you wish to see.
>>> S E T U P <<<
The SETUP module is the built-in data manager for the satellites and
observation points to be used in PC-TRACK. With it you can enter and edit,
and delete all information necessary to do satellite tracking with PC-TRACK
quite easily.
To select the SETUP module, move the cursor using the arrow keys to SETUP.
Then press the RETURN key. A second menu window will appear with the options
OBSERVERS and OBJECTS. The OBSERVERS option handles data for the observation
points and OBJECTS handles the data for the satellites. Select the desired
option by again moving the cursor to highlight the one you want.
There are various keys that will assist you in the entry and editing of
observer or object data while in the SETUP module. They are as follows:
F2 - ADD OBSERVER/OBJECT
This key allows you to create a new entry in the observer/object file where
information about a new observer/object can be put. When this key is pressed,
all the screen fields are cleared so you can begin entering new information.
F3 - REMOVE OBSERVER/OBJECT/OBJECT
This key does just the opposite of the F2 key. It PERMANENTLY removes the
currently visible observer/object from the file. Since this action is
PERMANENT and IRREVOCABLE, a warning window pops up to alert you to the fact
that this will occur if you continue. If you press RETURN in response to the
warning window prompt, you will remove that observer/object from the file.
If you press ESC or any other key, you will not remove the observer/object
and you will go back to where you were when you pressed the F3 key.
PAGE UP - PREVIOUS OBSERVER/OBJECT/OBJECT
This key will display the previous observer/object in the file.
Observer/objects are stored in the file in the order they are entered. Once
the observer/object you desire is visible on the screen, you may edit any
of the fields. If you step past the first observer/object in the file, the
last will be displayed.
PAGE DOWN - NEXT OBSERVER/OBJECT/OBJECT
This key will display the next observer/object in the file. If you go past
the last observer/object in the file, the first will be displayed.
SETUP OBSERVERS
The OBSERVERS option opens up the data entry window on the right hand side
of the screen. This window shows the six fields (pieces of information) held
for each observation point you have in the file.
The six pieces of information necessary to describe an
observation point are as follows:
DESCRIPTION:
This field is your way of easily identifying each of the observation points
you have in your file. This is a text field with room for up to 30 characters
(anything you want).
For example, you can put the names of the nearest associated city with the
state, such as Dayton, Ohio. Or if you have a lot of observation points
entered, you might devise some numbering system to systematic identify each
location. This could be something like OH-39N-84W, which would be a location
in the state of Ohio, near 39 north latitude and 84 west longitude. I'm sure
you can devise some more sensible system because as you see below the
latitude and longitude are already included with the description.
LATITUDE:
This along with longitude defines the location on earth of the observation
point.
Latitude is entered as degrees and decimal fractions of degrees. Latitude
will be entered as a positive number if it is in the northern hemisphere and
negative (-) for those in the southern hemisphere.
For example a position with a northern hemisphere latitude of 34 degrees, 30
minutes, and 15 seconds would be entered as 34.5694444. That same latitude
in the southern hemisphere would be entered as -34.5694444.
This may be entered as a number between -90.0 to 90.0.
LONGITUDE:
This along with latitude defines the location on earth of the observation
point.
Longitude is entered like latitude as degrees and decimal fractions of
degrees.
Longitude is entered as positive values for the western hemisphere (North and
South America, Greenland, etc.) and negative for the eastern hemisphere
(Europe, Asia, Russia, etc). This may be entered as a number between -180.0
and 180.0.
MINIMUM ELEVATION:
This figure describes the lowest elevation a satellite may be visible from
the observation point. An observation point with a perfectly clear horizon
around it would have a minimum elevation of 0.0 degrees. If there are
mountains or buildings around it the minimum elevation would be higher.
This may be entered as a number between 0.0 and 90.0.
This number is used as a filter for displaying and printing azimuth/elevation
data. Only satellite view angles with elevations above the minimum will be
displayed or printed.
TIME ZONE:
This describes the number of hours from UTC time (Coordinated Universal Time)
(used to be called GMT or Greenwich Mean Time) your local time zone is. Time
zones in the western hemisphere are positive while eastern hemisphere zones
are entered as negative.
For example, Eastern Standard Time would be entered as 5 hours from UTC time.
Pacific Standard Time would be 8 hours. If you wish your displays and
printouts to be in UTC time, enter 0 and make sure the DOS clock is set to
UTC time.
Time Zone may be entered as whole numbers between -12 and 12.
HEIGHT:
This describes the height in feet your observation point is above Mean Sea
Level (MSL).
If you are not sure what the height is for the observation point, enter 0.0.
Height may be entered as any value between -400.00 and 30,000 feet.
SETUP OBJECTS
The OBJECTS option also opens up the data entry window on the right hand side
of the screen. This window shows the twelve fields (pieces of information)
held for each object you have in the file. This information is available from
a number of sources. See appendix A for the cheapest and most reliable source
for this information. The twelve pieces of information necessary to describe
an object are as follows:
NAME:
This is a 20 character field which you can use to name the object for easy
identification.
CATALOG (OBJECT) NUMBER:
This is a 5 digit number assigned to each object. It is used as the reference
number in the NASA source identified in Appendix A.
EPOCH YEAR:
This is the year of the specific time the rest of the data about the object
is effective. When entering Epoch year, make sure you include all 4 digits
of the year, ie. 1989. Some data sets such as those from Nasa include only
the last 2 digits of the year. PC-Track requires all 4.
EPOCH DAY:
This is the day and fraction of day for the specific time the data is
effective. This number defines both the julian day (the whole number part of
the value) and the time of day (fractional part of the value) of the data
set.
The julian day figure is simply the count of the number of days that
particular date is from the beginning of the year. (January 1 would have a
julian day of 1. Feb 28 would be 59.)
This number may range from 1.0 to 366.999999999 (taking into account leap
years).
DECAY RATE:
This is the rate of decay of the orbital period (time it takes to complete
one revolution) due to atmospheric friction and other factors. It is a real
number measured in terms of Revolutions per Day per Day (REV/DAY/DAY).
INCLINATION:
This number describes the angle of the plane of the orbit in relationship to
the earths equator.
Inclination is 0 degrees for a object orbiting directly over the earths
equator and orbiting in the same direction as the earth's rotation. It is 180
degrees for an object revolving directly over the equator counter to earth's
rotation. An object orbiting directly over the poles would have an
inclination of 90 degrees.
Inclination is given as a real number of degrees between 0.0 and 180.0
degrees.
RIGHT ASCENSION OF ASCENDING NODE:
This value describes the point the satellites crosses the equator from the
southern hemisphere to the northern hemisphere (ascending node). This
measured eastward along the equator from the vernal equinox (right
ascension).
It is given and entered as a real number of degrees from 0.0 to 360.0
degrees.
ECCENTRICITY:
This is a unitless number which describes the shape of the orbit in terms of
how close to a perfect circle it is. This number is given in the range of 0.0
to less than 1.0.
An perfectly circular orbit would have an eccentricity of 0.0. A number
greater than 0.0 would represent an elliptical orbit with an increasingly
flattened shape as the value approaches 1.0.
ARGUMENT OF PERIGEE:
This value is the number of degrees from the ascending node the perigee point
occurs. The perigee point is the point where the satellite is the closest to
the earth (assuming an orbit which is elliptical to some degree).
This number may be entered as a real value between 0.0 and 360.0.
MEAN ANOMALY
This number represents the angular distance from the perigee point (closest
point) to the satellite's mean position. This is measured in degrees along
the orbital plane in the direction of motion.
This number is entered like the argument of perigee, as a value between 0.0
and 360.0.
MEAN MOTION:
This is the number of complete revolutions the satellite makes in one day.
This number may be entered as a value greater than 0.0 and less than 20.0.
When all of the pieces of information have been input for an object and you
have no other objects to enter, press ESC to get back to the main menu.
REVOLUTION NUMBER
This represents the number of revolutions the satellite has completed at the
epoch time and date.
This number is entered as an integer value between 1 and 99999.
>>> TRACK <<<
The TRACK module is the heart of PC-TRACK. It is where the graphical
presentation of the satellite position is done. Moving the cursor to this
option brings up a selection screen before going on to the track screen.
SELECT
This screen allows you to easily select an object and an observer from those
you have entered into the files using the SETUP option.
Your selections are made by simply using either the Up or Down Key. Once the
object or observation point is visible press RETURN.
After selecting which object to track and the observation point, you will be
asked to define what data is to be printed (if enabled) during track. You
have a choice of either printing every point computed or only those which
have satellite elevations from the observation point greater than the minimum
elevation entered for that point. Once the desired answer is provided by
using the Up or Down keys and pressing RETURN, tracking begins.
TRACK SCREEN
During the tracking process information is provided within a number of
separate boxes on the screen. The general locations of these boxes on the
track screen and the information presented are described below.
┌────────────────────────────────────────────────────────────┐
│ T I T L E B O X │
└────────────────────────────────────────────────────────────┘
┌─────────────┐┌────────────────────────────┐┌───────────────┐
│ STATUS BOX ││ DATE/TIME BOX ││ TIME INTERVAL │
└─────────────┘└────────────────────────────┘└───────────────┘
┌───────────────────────────────────────┐┌───────────────────┐
│ ││ │
│ ││ │
│ O B J E C T B O X ││ S T A T I O N │
│ ││ │
│ ││ B O X │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
│ ││ │
└───────────────────────────────────────┘│ │
┌───────────────────────────────────────┐│ │
│ H E L P B O X ││ │
└───────────────────────────────────────┘└───────────────────┘
TITLE BOX
This shows the title of the program and the name of its author. This is
presented across the top of the screen.
STATUS BOX
This box shows the status of the various modes available for selection during
the selection process. The messages which will show up in this box are as
follows...
Real Time Track - Indicates PC-TRACK is tracking the satellite in real time.
Fast Track - Indicates PC-TRACK is computing and displaying satellite
positions as fast as possible ignoring the internal clock.
Pausing - Indicates PC-TRACK has temporarily halted the tracking process and
is waiting for the F3 key to be pressed again to resume tracking.
Printing - Indicates PC-TRACK is enabled to send tracking data to the
printer. The amount of data sent to the printer is determined by the type of
data selected during the SELECT process just before tracking began.
DATE TIME BOX
PC-TRACK is a time based tracking package, which means that it first
generates a time and date and then figures out where the satellite is at that
time and date. Therefore, the central display is the time and date of the
current satellite position. This box is just below the title box in the upper
center of the screen.
TIME INTERVAL BOX
The time interval box displays the current time interval used in picking each
time used to compute the satellites position.
The interval is added to the current track time (shown in the DATE TIME BOX)
to generate the next time to compute the satellite position. This interval
is initially set to 1 second. It may be modified by various function key
combinations as described below when in the Fast Track Mode. Interval is
fixed at 1 second in Real Time Mode.
For example if the current time shown in the DATE TIME BOX is 09:03:32, and
the interval is 00:00:05 (5 seconds) then the next time that will be used to
compute the satellite position is 09:03:37. The time Interval remains wher
you set as long as PC-Track is running.
OBJECT BOX
The object box shows all the information relating to the current satellite
position.
Object Name and Revolution
At the top of the box the name of the satellite is shown along with the
current revolution number.
Map
The center of the box contains the mercator projection world map which is
where the satellite position is shown graphically. Each computed satellite
position is shown on the map as a yellow dot. As more and more points are
plotted, a ground track will eventually be evident on the map.
Latitude and longitude lines are shown on the map for reference purposes.
Help Screen
When the F1 help key is pressed the world map area is used by the PC-TRACK
ASSISTANT to display the various help screens. This is the very same help
system used in other parts of the program. When you are done with the help
system, press ESC and the world map will be restored as it was when help was
requested.
Position and Altitude
Finally the bottom of the screen shows numerically the current satellite
position in latitude and longitude. Also shown is the current altitude of the
satellite in miles.
STATION BOX
Next to the object box is the STATION BOX. This box displays information
which is related to the observation point, including the current relationship
between the observation point and the current satellite position.
Observation Point Info
At the top of the box is the information describing the observation point,
specifically the Description, Latitude, Longitude, Height, Time Zone, and
Minimum Elevation for that point.
Azimuth/Elevation Chart
Below the observation point info is a chart which graphically shows the
current relationship between the observation point and the object. This
chart is read as follows:
A point will be placed on the chart based on the current azimuth (bearing)
and elevation needed to point an antenna at the object from the observation
point.
The distance from the center of the chart represents the current elevation.
The farther the point is from the center, the lower the elevation. This is
indicated by the numbers shown along the horizontal line on the chart. The
center represents 90 degrees elevation or directly overhead. The angular
position from the vertical line represents the azimuth from the observation
point to the satellite. The azimuths are numbered clockwise around the
outside of the outermost circle drawn on the chart. Zero degrees azimuth is
true north.
Azimuth, Elevation, and Slant Range
Below the Azimuth/Elevation chart is a box which numerically show the
observation point/object relationship. In this box the Azimuth, Elevation
and Slant Range are shown.
The slant range is the straight line distance from the observation point to
the satellite at its current position. This figure is shown in miles.
HELP BOX
The HELP BOX is a handy reminder of the various key commands available for
use during the tracking process. This is a summary of the commands, for
details press the F1 key.
FUNCTION KEYS
There are several function keys set up to control various features of PC-
TRACK which affect the tracking process. They are described as follows...
F1 - Help
This is the key which brings up the PC-TRACK ASSISTANT as described earlier.
It functions exactly as it does anywhere else in the program except the help
screens show in the area of the world map. Once you exit the help system, the
world map is restored to its original condition before help began.
F2 - Real Time / Fast Track
This key controls the tracking mode of PC-TRACK. When tracking first begins,
it is in the REAL TIME TRACK mode. This means the position displayed
represents the actual satellite position according to the time set in the
computer (DOS time). The displays will be updated at the time interval shown
in the TIME INTERVAL BOX (fixed to 1 second).
Pressing the F2 key changes this to the FAST TRACK mode. This mode ignores
the clock in the computer and simply computes and displays the satellite
positions as fast as it can. The time between each point computed is
determined by the time interval shown in the TIME INTERVAL box. This time
interval is changeable according to the procedures shown below.
The F2 key acts as a "toggle". This means that if you press it once, the mode
changes to FAST TRACK. When you press it again, the mode changes back to REAL
TIME TRACK. Pressing it again changes the mode again to FAST TRACK, etc.
F3 - Pause Tracking
This key may be pressed at any time during tracking to "freeze" the display.
This stops all computations and simply waits for the F3 key to be pressed
again. Once it is pressed again, normal tracking resumes. While in the pause
mode, you may make changes to the time increment (described below), turn the
printer on or off, and select Real Time or Fast Track mode.
F4 - Enable Printer
This key enables output to be sent to the printer during the tracking
process. The amount of data sent to the printer is determined by your
response to the prompt during the SELECT process just before tracking began,
either all data or just points with elevations above the minimum elevation.
The F4 key operates as a toggle just as the F2 and F3 keys. If printing is
enabled, just press F4 again to turn it off.
F5 - Redraw Screen
The F5 key simply redraws the World Map and the Azimuth/Elevation chart to
remove clutter from extended tracking.
CTRL F1-F5 - Decrease Time Interval
By pressing and holding the control key (CTRL) and at the same time pressing
either F1, F2, F3, F4, or F5 the time interval may be decreased. The
following chart shows how each key affects the time interval.
HR MN SEC
TIME INCREMENT 00:00:00
■ ■■ ■■
│ ││ ││
CTRL F1 ■─┘ ││ ││
CTRL F2 ■───┘│ ││
CTRL F3 ■────┘ ││
CTRL F4 ■──────┘│
CTRL F5 ■───────┘
Please notice that the time interval can be made to go negative. This is a
feature of PC-TRACK which allows you to track backwards in time to enable you
to get to a specific point in time for analysis.
ALT F1-F5 - Increase Time Interval
By pressing and holding the alt key (ALT) and at the same time pressing
either F1, F2, F3, F4, or F5 the time interval may be increased. The
following chart shows how each key affects the time interval.
HR MN SEC
TIME INCREMENT 00:00:00
■ ■■ ■■
│ ││ ││
ALT F1 ■─┘ ││ ││
ALT F2 ■───┘│ ││
ALT F3 ■────┘ ││
ALT F4 ■──────┘│
ALT F5 ■───────┘
>>> CONFIGURATION <<<
This module allows you to modify certain things about the program which
affect the way the program operates. The things you can change are text
screen colors, printer control codes, and the data file subdirectory.
CONFIGURE SCREEN
This option allows you to easily change the colors you see on the text
screen displays. This way you can get the screen displays to look the way
you want. This also makes it easy to adjust displays on monochrome monitors.
You are able to see the effects of changes on the screen while you make
them. You can make changes to both the background and text colors with
simple key strokes. Here's how to do it...
Information is displayed on the screen using 7 different categories for the
text and background colors...
- NORMAL
- HIGHLIGHTED
- DATA ENTRY
- TITLE
- SCREEN COLOR
- SHADOW COLOR (Background only)
Only the combinations used in PC-TRACK are shown. The colors for both the
background and text colors can be selected for each of these categories.
Selecting Text Color Category
Using the Left and Right arrow keys selects the category for text color
changes. The currently selected category is shown by a down arrow pointing
to it along the top of the matrix.
Select Background Category
Use the Up and Down arrow keys to select the category for background color
changes. The currently selected category is shown by a right arrow pointing
to it along the left side of the matrix.
Change Text Color (F5)
Pressing this key changes the color of the currently selected text category.
There are 16 colors to choose from.
Change Background Color (F6)
Pressing this key changes the color of the currently selected background
category. There are 2 sets of 8 identical colors. One set causes the text to
be non-blinking while the other causes blinking text.
CONFIGURE SYSTEM
This option allows you to change the control codes sent to your printer to
make it print the PC-TRACK reports correctly. It also allows you to define
where PC-TRACK looks on your disk to find the files it needs to operate
with.
Printer Codes
Printer codes are sequences of special control characters sent to your
printer. PC-TRACK displays and accepts them from you as the decimal
equivalents of each control character separated by a slash (/). For example,
the ESC character has a decimal value of 27 so it is shown on the screen
that way. Notice each print command has a code sequence to turn it on and one
to turn it off. Some codes do not need to be turned off, so those portions
are left blank.
Some printers may not be capable of printing certain features shown on the
screen, in that case, leave the CODE TO TURN ON blank for that feature. You
have up to 20 characters to define the turn-on or turn-off codes, including
the slashes.
You may move the cursor around on the screen to the desired code sequence
by using the arrow keys or just pressing RETURN.
Data Path
This line tells PC-TRACK what disk drive and what directories and
subdirectory on that disk to use as the storage area for the data files it
uses. This line of text will be in the form of an MS-DOS path name. If you
just want to tell PC-TRACK to use the B drive, just enter "B:" here. If you
have PC-TRACK on your hard disk and it is the C drive and you have a special
subdirectory called "\PCT\DATA", then you would enter "C:\PCT\DATA\" on this
line. (Please make sure to add the final backslash "\" to the path entered.)
APPENDIX A
OBTAINING SATELLITE INFORMATION
The information required by PC-TRACK can be obtained by requesting the
"NASA PREDICTION BULLETIN" or the "TWO LINE ORBITAL ELEMENTS" for each of the
objects desired, referenced by CATALOG NUMBER from:
PROJECT OPERATIONS BRANCH (CODE 513)
NASA/GODDARD SPACE FLIGHT CENTER
GREENBELT, MD. 20771
You may also request a package of prediction bulletins for certain
categories of objects such as weather or amateur radio satellites rather than
by individual CATALOG NUMBERS.
If you do not know the CATALOG NUMBER of the satellites you wish to order
data for, you can request the current "SATELLITE SITUATION REPORT". There is
no charge for this document and it can also be obtained from the above
address.
The Satellite Situation Report lists almost every object currently in
orbit. Each object is cataloged by the International Designation and by
Catalog number. It also lists the name, launch date, orbital period in
minutes, inclination, apogee, perigee, and transmitting frequency. By using
this document you can determine the catalog numbers of the objects you wish
to track with PC-TRACK.
APPENDIX B
HOW TO USE THE ORBITAL DATA FROM NASA
The data required by PC-TRACK is contained in the Two Line Orbital Elements.
As described above, these elements are a part of the Nasa Prediction Bulletin
described in Appendix A. The following is an example of the format of the
elements received from Nasa.
The Two Line Orbital Elements look like this when you get them from
Nasa...
1 13923U 83153.41230725 0.00000215 11423-3 0 376
2 13923 98.7483 183.1938 0017844 74.4610 285.8536 14.22303248 9340
Here are the pieces that PC-TRACK requires, broken out for you...
LINE 1
EPOCH YEAR PERIOD DECAY
■■ RATE │
■■ ■─────┴──■
1 13923U 83153.41230725 0.00000215 11423-3 0 376
■ ■ ■ ■ ■
│ └─────┬────┘ └──────┬──────┘
│ ■ │
│ EPOCH DAY.FRACTION ■
│ NOT USED
└───■ CATALOG NUMBER
(ignore letter)
LINE 2
CATALOG
NUMBER
■
│ INCLINATION ECCENTRICITY MEAN ANOMALY
│ ■ ■ ■
│ │ RIGHT ASC. │ ARGUMENT │ MEAN MOTION
┌───┤ ┌────┴┐ OF NODE │ OF PERIGEE │ ■
■ ■ ■ ■ ■────┴─■ ■─────┘ ■────┴■ ■─────┴■ ■────┴────■
2 13923 98.7483 183.1938 0017844 74.4610 285.8536 14.22603248 9340
■┬─■
│
REVOLUTION NUMBER■──┘
AT EPOCH
NOTICE THAT THERE IS NO DECIMAL POINT PRINTED FOR ECCENTRICITY. THE DECIMAL
POINT GOES IN FRONT OF THE NUMBER. FOR EXAMPLE, THE NUMBER SHOWN ABOVE FOR
ECCENTRICITY WOULD BE ENTERED AS .0017844.
APPENDIX F
G L O S S A R Y
The following are some terms used in the satellite tracking business and are
described in layman's terms.
APOGEE
The point in a satellite's orbit farthest from the Earth's center.
ARGUMENT OF PERIGEE
The angular distance measured in the orbit plane, in the direction of motion
of the satellite, from the point of intersection of the orbit and equatorial
planes, to the perigee point. The perigee point is the point in the orbit
where the satellite is closest to the earth's surface.
ASCENDING NODE
Point at which the satellite crosses the equatorial plane from the
southern hemisphere to the northern hemisphere. (See also RIGHT ASCENSION OF
THE ASCENDING NODE.)
AZIMUTH
The angle measured in the plane of the horizon from true North clockwise to
the vertical plane through the satellite.
CATALOG NUMBER
A 5 digit number assigned to a cataloged orbiting object. This number may be
found in the Nasa Satellite Situation Report and on the Nasa Prediction
Bulletins.
COORDINATED UNIVERSAL TIME (UTC)
Also known as Greenwich Mean Time (GMT). Local time at zero degrees
longitude at the Greenwich Observatory, England. Uses 24 hour clock, ie. 2:00
pm is 1400 hrs.
CULMINATION
The point at which a satellite reaches its highest position or elevation in
the sky relative to an observer. (Also known as the Closest Point of
Approach)
DECLINATION
The angular distance from the equator to the satellite measured positive
north and negative south.
DRAG
The force exerted on a satellite by its passage through the atmosphere of the
Earth, acting to slow the satellite down.
ECCENTRICITY
The degree of flattening of the orbit or its departure from a circle. The
greater the eccentricity, the more elliptical the orbit is.
ELEMENT SET
See ORBITAL ELEMENTS.
EPHEMERIS
A tabulation of a series of points which define the position and motion of
a satellite.
EPOCH
A specific time and date which is used as a point of reference; the time at
which an element set for a satellite was last updated.
EQUATORIAL PLANE
An imaginary plane running through the center of the earth and the Earth's
equator.
INCLINATION
The angle between the orbit plane and the Earth's equatorial plane, measured
counter-clockwise. 0 (zero) degrees inclination would describe a satellite
orbiting in the same direction as the Earth's rotation directly above the
equator (orbit plane = equatorial plane). 90 degrees inclination would have
the satellite orbiting directly over both poles of the earth (orbit plane
displaced 90 degrees from the equatorial plane). An inclination of 180
degrees would have the satellite orbiting again directly over the equator,
but in the opposite direction of the Earth's rotation.
INTERNATIONAL DESIGNATOR
An internationally agreed upon naming convention for satellites. Contains the
last two digits of the launch year, the launch number of the year and the
piece of the launch, ie. A-indicates payload, B-the rocket booster, or second
payload, etc.
LATITUDE
Also called the geodetic latitude. the angle between the perpendicular to the
Earth's surface (plane of the horizon) at a location and the equatorial plane
of the earth.
LONGITUDE
The angular distance from the Greenwich (zero degree) meridian, along the
equator. This can is measured either east or west to the 180th meridian (180
degrees) or 0 to 360 degrees west. For example, Ohio includes 85 degrees west
longitude, while India includes 85 degrees east longitude. But 85 degrees
east longitude could also be measured as 275 degrees west longitude.
MEAN ANOMALY
Angular distance measured in the orbit plane, in the direction of motion,
from the perigee point to the satellite's mean position.
MEAN MOTION
The number of complete revolutions a satellite makes in a given unit of time,
usually measured in revolutions per day. (see also DECAY)
NASA PREDICTION BULLETINS
Report published by Nasa Goddard Space Flight Center providing latest orbital
information on a particular satellite. This report gives information in 3
parts: 1) two line orbital elements, 2) Longitude of the South to North
equatorial crossings, and 3) longitude and heights of the satellite crossings
for other latitudes (besides the 0 degree latitude shown in part two).
ORBITAL ELEMENTS
Also called Classical Elements, Satellite Elements, Element Set, etc.
Includes the catalog Number; epoch year, day, and fraction of day; period
decay rate; argument of perigee, inclination, eccentricity; right ascension
of ascending node; mean anomaly; mean motion; revolution number at epoch; and
element set number. This data is contained in the TWO LINE ORBITAL ELEMENTS
provided by Nasa in the Nasa Prediction Bulletin.
PERIOD DECAY RATE
Also known as Decay. This is the tendency of a satellite to lose orbital
velocity due to the influence of atmospheric drag and gravitational forces.
A decaying object eventually impacts with the surface of the Earth or burns
up in the atmosphere. This parameter directly affects the satellite's MEAN
MOTION. This is measured in various ways but PC-TRACK, the Nasa Prediction
Bulletins and the Two Line Orbital Elements use revolutions per day per day.
PERIGEE - The point in the satellite's orbit where it is closest to the
surface of the earth.
POSIGRADE ORBIT
Satellite motion which is in the same direction as the rotation of the Earth.
RETROGRADE ORBIT
Satellite motion which is opposite in direction to the rotation of the Earth.
REVOLUTION NUMBER AT EPOCH
The number of revolutions or ascending node passages that a satellite has
completed at the time (epoch) of the element set since it was launched. The
orbit number from launch to the first ascending node is designated zero,
thereafter the number increases by one at each ascending node.
RIGHT ASCENSION OF THE ASCENDING NODE
The angular distance from the vernal equinox measured eastward in the
equatorial plane to the point of intersection of the orbit plane where the
satellite crosses the equatorial plane from south to north.
SATELLITE SITUATION REPORT
A report published by Nasa Goddard Space Flight Center listing all known man-
made Earth orbiting objects. This report lists the Catalog Number,
International Designator, Name, Country of origin, launch date, orbital
period, inclination, beacon frequency, and status (orbiting or decayed).
TWO LINE ORBITAL ELEMENTS
See ORBITAL ELEMENTS.
VERNAL EQUINOX
Also known as the first point of Aries, being the point where the Sun crosses
the Earth's equator going from south to north in the spring. This point in
space is essentially fixed and represents the reference axis of a coordinate
system used extensively in Astronomy and Astrodynamics.